Method of shelling nuts



April 8, 1941. D. B. MACFARLANE mmabn 0F SHELLING uu'rs Filed Oct. 22, 1958 2 Sheets-Sheet l IN VENTOR H/fi A TTORNEY D. B. MACFARLANE METHOD OF SHELLING NUTS April 8, 1941.

Filed Oct. 22, 1938 I 2 Sheets-Sheet 2 HA5 .4 TTORNE Y Patented Apr. 8, 1941 2,237,442 METHOD or snrznmvo more Donald B. Maci'arlanc, Berkeley, Calif.

Application October 22, 1938, Serial No. 236,492

(or. etar) 4 @lairns.

My invention relates to the shelling of nuts, such as English-walnuts; and the broad object oi" the invention is to provide a method for auto matically separating-the shells from. the nut meats.

Another object ,of the invention is to provide a method embodying a step of treating the nuts before cracking to impart to the shells a characteristic different from that of themeats.

Another object is to provide a method relying upon means responsive to the differential characteristic for separating the shells from the meats.

Another object is to provide a method of the character described in which the nuts are treated by coating them with a material to alter the specific gravity of the shells relative to that of the meats, whereby the weight differential thus imparted may be utilized to effect separation, as by flotation.

A further object is to provide a method embodying the additional step of recovering the coating from the shells after separation.

The invention possesses other objects and teatures of advantage, some of which, with the foregoing, will be set forth in the following descripi tionof my invention. It is to beunderstood that I do not limit myself to this disclosure of species of my invention, as I may adopt variant embodimerits thereof within the scope of the claims.

- Referring to, the drawings:

Figure l is a diagrammatic view, partly in section and partly in elevation, showing apparatus for carrying out a method embodyim the im provements of my invention.

Figure 2 is an axial sectional view of the coating trommel; and

Figure 3. is a vertical sectional view 'of the flotation tank.

Figure 4 is a horizontal sectional view of the nut meat drier.

- The shelling of nuts. such as English walnuts, is a diflicuit problem in commercial practice; the

penal procedure being to crack the nuts in a suitable cracking machine and then separating the nut meats from the shells by hand. This hand.

picking of the meats involves a great deal of labor and is a time taking and expensive procedure when thousands of pounds of nuts are being handled. Hand picking is resorted to because there is no differential characteristic, such as a difference in weight. that can be relied upon tion or other separating means. The shells and =i0 effect separation by mechanical devices, flotasame specific gravity; some of the shell particles alter cracking lacing heavier than the meats, and some of the meats being heavier than other shell particles. The size of the shell and meat particles is also sumciently the same to render impossible mechanical separation relying upon such a diflerence.

I have solved the problem of shelling nuts, such as English walnuts, by treating the nuts before cracking to impart an artificial characteristic to the-shells (such as increasing the weight of the shells), which characteristic is different from that of the meats and may be relied upon to effect an automatic separation of the shells and meats, as by flotation.

In terms of broad inclusion, the method of shells relative to that of the nut meats, and subsequently the cracked shells are separated from the meats by flotation.

In greater detail. and referring particularly to the diagrammatic view in Figure 1 of the drawings, a nut shelling apparatus for practicing the method of my invention comprises a coating unit including an inclined trommei 2, into one end'oi which nuts to be shelled are introduced from a hopper 3. The nuts are coated with a suitable material from a tank 4 and introduced into the trommel by a pump 8 through a spray nozzle I. In the apparatus being described, where liquid flotation is employed for separation, the coating material applied to the nut shells preferably comprises a paint including a dense material, such as metal, to add weight to the shells. I preferably use a copper-bronze powder 1 and having a down spout 9 for draining the excess material back into supply tank 4. From trommel 2 the freshly coated nuts roll down a' I trough Ill having perforations along the underside to further drain excess fluid back in tank 4 in the drum to divide the upper end from the apertured lower portion. This partitioning also provides a reservoir for coating fluid in whichthe nuts may roll to supplement the coating action of spray nozzle 1. The coated nuts gradually work down over the partitions and out the lower. end of the drum into trough i0.

Means are provided for drying the coated nuts. For this purpose a drying tower It is provided for receiving the nuts from trough l0. Warm air is forced into the lower end of the tower from a suitable source by a blower 15. The air is admitted from a restricted annular opening formed by a pair of cones I6 and H; the upper end of the inner cone roviding a central opening through which nuts in the tower may drop. As the nuts fall into the tower they are caught by the air stream and then slowly fall against the moving column of drying air; the latter being regulated to effect complete drying of the coating before the nuts reach the bottom of the tower. Upper portion 18 of the tower is preferably enlarged above the point where the nuts enter, so as to reduce the force of air draft to prevent the air from carrying the good nuts out the top of the tower. The draft may be adjusted however .to blow the lighter nuts or culls out the top.

Means are provided for cracking the nuts. Any suitable nut cracking machine, indicated diagrammatically at i9, may be provided; and is arranged to receive nuts, as by a conveyor 2!, from the bottom of the drying tower. The cracking machine is preferably of a type which breaks the shells into small pieces, so that the nut meats are completely released from the shells.

Means are also provided for separating the shells from the meats. For purposes of illustration I show a liquid flotation tank 22 into which the cracked .shells and nut meats, are dumped from a suitable conveyor 23 and separated by gravity. It is understood that other kinds of coating materials may be employed which will alter the relative responsiveness of the shell and meats to applied forces other than gravity, in order to effect the separation. For example, electrostatic or magnetic forces may be employed for separation, to which the coating material selected is sensitive. Also, other means relying upon a weight differential may be employed, such as air 'fiotation, centrifuging or shaking ona jig. It is also understood that with separating devices depending upon weight differential, the nuts may be coated with a spongy material to make the shells lighter instead of heavier than the meats.

In a liquid flotationtank designed to separate the meats from heavier shell particles, as shown, the liquid used is preferably an ordinary salt solution of a density calculated to float the meats and allow the coated shells to sink to the bottom. The nuts are preferably introduced through a funnel 24 and are carried down well into the brine by a recirculating stream of fluid discharging into funnel 24 from a pipe 26.

adjacent the surface, and a pump 21 is provided to effect circulation.

This pipe draws brine from the opposite end of the tank The nut particles are carried down with the discharging stream, and the lighter meats then float up toward the top, leaving the heavier shells at the bottom. Baifie plates 2li across the tank tend to break up the circulation in the tank and give time for the nut particles to be properly separated. See Figure 3. Bottom 29 of the tank is inclined so that the shells settling out move down to one end where they may be removed by suitable means, as by a chain ladder 3i.

Nut meats floating to the top are gradually carried over to the discharge end by the circulation in the tank, and are removed by suitable means, as by a paddle wheel 32. The meats are prevented from being drawn into the circulating duct by a screen 33 adjacent the wheel. A chute (it is arranged to catch the meats lifted out by the wheel and direct them to a suitable elevator 30, such as one having a screw 37, for conveying the meats to another unit of the apparatus.

Means are preferably provided for drying the nut meats. after being removed from flotation tank 22. For this purpose a centrifugal drier and blower unit is arranged to receive the meats from a chute 39 leading from elevator 36. As shown in Figures 1 and 4, the unit comprises a casing 6i having a tangential outlet duct [2. A rotor 'is mounted, within the casing and comprises an apertured cylindrical portion 33 having outwardly projecting fan blades 65 running in the blower chamber 46 of the casing. The rotor also has upper and lower conical sections ll and 68, open attop and bottom for receiving and discharging the nut meats.

The entire rotating element is mounted on a shaft 69 driven by suitable means, not shown; and an outwardly flaring plate M is arranged on the shaft below the inlet to deflect the meats outwardly against the apertured walls of the rotor. A screen lining 52 prevents the small meat particles from passing through the apertured walls. As the wet meats pass downwardly through the whirling rotor the moisture is thrown oil by centrifugal force, and the meats are further dried by the air draft drawn in through the ends of the rotor and passing outwardly through the screened openings by the blower action of blades 66. The moisture laden air is thus carried off by duct 42, and the dry meats fall into a chute 53 for delivery to a conveyor 54. The meats are preferably then graded for color by a suitable machine, not shown.

It is understood that if a type of separating means is employed that does not involve wetting the meats, the drying unit is not required and the separated meats may go directly to the color grading machine.

Since the shelling of nuts, such as English walnuts, is a large scale operation, involving the shelling of more than 100,000 pounds of walnuts per day, the salvaging of the coating material applied to the shells is desirable. To this end I take the shells from ladder 3i and carry them on an air stream forced through a duct 56 by a blower 51. This dries the shells and conveys them to a cyclone 58 where the shells are separated from the air stream and fall through a down spout 59 into a tank 6i.

Tank 6i contains a solvent, such as acetone. for the paint, and the shells are washed in the solution by agitation .created by a recirculating pump 62 for withdrawing fluid from the top of the tank through a ductv 63 and discharging it at the bottom. The dissolved paint and metallic Wh t-til pump and returned to coating tank t through a duct ill.

The Washed shells are picked up by a chain ladder adjacent the screened inlet W of the recirculating duct, to which the shells are drawn by the fluid circulation. The shells then drop through a chute ill to a conveyor it upon which they are carried to any desirable pointoi disposal. Fluid level in tank ti is preferably maintained. by float valve lil controlling inflovr of solvent from a supply tanlr it. if desired, a suitahle trap it may he arranged in duct ill to catch any salt Water that might he carried over with the shells from the flotation tanlr.

another saving may he effected in the apparatus by connecting the upper end, of drying tower ill With an absorption tower (not shown) associated with a still and condenser for collecting the "evaporated solvent (acetone).

While I have described several pieces of equipment, such as the coating recovery means, in conjunction with my apparatus, it is understood that these may he employed or omitted as desired in a given installation, depending upon Whether the recoveries made Warrant the additional equipment. The broad combination or method steps remains the same, namely, the step embodying means (such as coating unit ill) for treating the nuts to impart to the shells a characteristic different from the nut meats (such as a differential in specific gravity); the step emhodying means (craclring machine it) for cracking the nuts to release the meats; and the step emhodyingmeans (such as flotation tanlr ill) responsive to the differential characteristic for separating the shells irom the meats.

l claim:

it The method oi shellina nuts, which comprises applying to the nuts an adherent coating which alters the relative responsiveness oi the shells and the meats to an applied force, cracking the coated nuts to release the meats, and then applying such force to the mixed meats and shells to effect the separation thereol hy the utilisation oi the dlflerential characteristics afforded by the presence of said coating on the shells.

fl. The method of shelling nuts, which comprises fliting metallic material upon the shells heiore craclrlng the nuts which alters the relative responsiveness oi the shells and the meats to an applied force, craclcing the nuts to release the meats from the metalliaed shells, and then applying such force to the mined meats and shells to eiiect the separation thereot hy the utilization of the differential characteristics aiiorded lay the presence oi said metallic material on the shells.

3. The method oi shelling nuts, which cornprises flirting metallic material upon the shells heiore 'craclring the nuts Which alters the relative responsiveness oi the shells and the meets to an applied iorce, craclring the nuts to release the meats izrorn the metalliaed shells, applying such force to the mired meats and shells to efiect the separation thereoi" lay the utilisation oi the dillerentiai characteristics arlorded hy the presence of said metallic material on the shells, and then recovering the metallic deposit irom the shells.

at. The method oi shelling nuts, which comprises applying to the nuts an adherent coating which alters the relative responsiveness of the shells and meats to an applied force, cracking the coated nuts to release the meats, applying such iorce to the mixed meats and shells to eil'ect the separation thereof hy the utilisation of the differential characteristics allorrled hy the presence oi. said coating on the shells, and then dissolving the coating material to recover the same from the shells.

llllUNlllhlIll H. 

